Classification
333 - Economics of land & energy
6
330 - Economics
4
320 - Political science
3
363 - Other social problems & services
2
380 - Commerce, communications & transportation
2
551 - Geology, hydrology & meteorology
2
600 - Technology
2
620 - Engineering & allied operations
2
700 - The arts; fine & decorative arts
2
140 - Specific philosophical schools
1
304 - Factors affecting social behavior
1
338 - Production
1
580 - Plants (Botany)
1
581 - Specific topics in natural history
1
630 - Agriculture & related technologies
1
800 - Literature & rhetoric
1
900 - History & geography
1